Activists at Occupy Wall Street have issued a call to thousands of protesters across the US to reoccupy outdoor public spaces to mark the movement's three-month anniversary.

The Occupy movement has stalled in recent weeks after a wave of evictions swept away a raft of encampments, including the largest in Los Angeles, Philadelphia and New York. On Wednesday, it suffered a fresh blow as police in riot gear cleared Occupy San Francisco camp on the orders of the mayor, who had been sympathetic to protesters, while Occupy Boston lost legal protection against eviction.

Organisers said they hoped the call to reoccupy on the 17 December would galvanise and grow the movement.

Amin Husain, a press spokesman for OWS, said: "We know that occupation empowers people and eliminates fear. It permits individuals to assert themselves as political beings even although the system doesn't represent them."

"The question is not to make a splash, the question is how are we going to get the space to make that happen."

Sandy Nurse, one of the direct action committee responsible for the call, said: "The need for physical space is one of the top five priorities for direct action. My personal opinion is that people have gotten scared. They have gotten arrest fatigue. They are not willing to put their bodies on the line. But the call would re-galvanise the movement and remind it how powerful it is."

Citing the conference call by mayors across the US to deal with various encampments, Nurse said: "They have identified occupation as a threat to them – that's how powerful it is."

Eleven mayors participated in a conference call in November about Occupy protests in their cities, including those in New York, Denver and Portland, Oregon, but they denied any co-ordination of raids to clear encampments.

The need for a physical space has been on OWS's agenda since police raided Zuccotti Park in November. In a piece published this week in the first issue of Tidal, a magazine published by the Occupy movement, Judith Butler, academic and feminist theorist at the University of California, Berkeley, spoke of its importance.

Butler said: "When bodies gather together as they do to express their indignation and to enact their plural existence in public space, they are also making broader demands. They are demanding to be recognised and to be valued; they are exercising a right to appear and to exercise freedom; they are calling for a liveable life.

"These values are presupposed by particular demands, but they also demand a more fundamental restructuring of our socio-economic and political order."

At one point, the movement had more than 1,000 occupations, but now they have less than 100 – and that number is dwindling daily. With the onset of winter's plummeting temperatures – which was already driving people from Zuccotti Park before the eviction – and the hardening attitudes of city authorities against encampments, notwithstanding the dearth of public spaces in the US, seeking a place to camp is a massive challenge for activists.

Even within OWS, where the movement began, activists have a battle on their hands. In Zuccotti Park, the space's owners have imposed strictly enforced rules which no longer allow tents or sleeping bags, or allow people to lie down, which would make it impossible to set up camp.

The place they want to occupy on December 17, is Juan Pablo Duarte Square, a currently vacant lot on the corner of 6th and Canal Street in Soho, about 15 minutes walk' from Wall Street, named after the founder of the Dominican Republic.

But it has already proved controversial.

It is owned by the real estate branch of Trinity Episcopalian church in Wall Street, Trinity Real Estate, one of the largest real estate companies in New York.

Activists at OWS, which had previously counted Trinity church among their supporters, have repeatedly asked for the use of this space for a winter camp. But Trinity church has refused, drawing criticism from other church leaders and a handful of activists who went on hunger strike, pledging not to eat until the church allowed protesters on the site.

In a statement on its website, Trinity said it offered its continued support of the movement – including providing meeting space at church buildings – but not the use of its enclosed vacant lot at the city-owned Duarte Square, which it leases to the Lower Manhattan Cultural Council. The property, Trinity said, is unsuitable "for large-scale assemblies or encampments."

For activists, the matter is simple: they need the space and the church should hand it over.

Husain said: "They're part of the 1% and they are choosing profit over God."

The church is also facing pressure from the religious community.

Reverend John Metz, of the Episcopalian Church of the Ascension, in Brooklyn, who describes himself as a "real mainstream church guy" said: "Trinity church is in a challenging position. They are a church with an enormous real estate holding. It's one thing to deliberate and review grants. It's another thing for a church to respond in real time to one of the largest movement for social change that this country has see for four decades.

"This is an opportunity to engage in mutual actions to transform a space, and make it a catalyst for the revitalisation of public squares that have all been eliminated in the United States, to create a space where the cause for social justice can be forwarded."